ABC7's data analysis found the Bay Area's average daily COVID case rate is four times more than what was reported a mere three weeks ago.
In the beginning of July, on average 231 new daily COVID cases were reported across the Bay Area. A mere three weeks later on July 21, that daily average is 978 new COVID cases.
RELATED: 'Pandemic of the unvaccinated': Bay Area doctor says cases could overwhelm hospitals within 4 weeks
"It's unbelievable," said Dr. Maria Raven, the Chief of Emergency Medicine at UCSF. "I didn't expect to see this, given our high rates of vaccination."
Raven says the next two weeks will be the most crucial time period to assess whether the masking recommendation will turn into a mandate.
"I think the next two weeks is going to tell us a lot because it's going to continue to give us more data on the Delta variant and what it's causing among these breakthrough infections in vaccinated people," she said.
In the past couple weeks UCSF reported around 20 breakthrough cases among vaccinated individuals - most with mild symptoms, but some patients were still hospitalized.
RELATED: Stanford students concerned about breakthrough COVID cases after 7 fully vaccinated test positive
"We've been seeing around one to two a day," said Raven. "It gives me pause, because it's not what I thought what we're going to see... people that are coming to the emergency department that are worried they have COVID and have symptoms."
In early July, UCSF had zero COVID hospitalizations and by July 23 the emergency room has 17 hospitalized patients - 10 of which are in the ICU. That same trend rising across the Bay Area at a rate we haven't seen since March.
"So we do expect that the number of infections will keep going up for at least a few weeks," said Stanford Infectious Disease Physician Yvonne Maldonado. "We expect hospitalizations to follow."
WATCH: Doctor explains your chances of contracting virus after vaccination
Dr. Maldonado says there's never been a more dangerous time for unvaccinated people.
In roughly the past month, both COVID hospitalizations and ICU admissions have more than doubled. On June 22, there were 166 hospitalizations across the Bay Area - that jumped to 412 hospitalizations on July 21. During that same time period, ICU admissions spiked from 50 to 119.
"I'm worried about the fall in particular when we generally tend to see more people indoors and worry about other viruses as well," said Maldonado.
VACCINE TRACKER: How California is doing, when you can get a coronavirus vaccine
Having trouble loading the tracker above? Click here to open it in a new window.
RELATED STORIES & VIDEOS:
- Everything to know about California's reopening
- Where you still have to wear a mask in CA
- Poll: What do you think about California's June 15 reopening?
- Cheat sheet: What you can and can't do after being fully vaccinated
- Can a workplace require the coronavirus vaccine? Here's what we found
- COVID-19 vaccine: Everything to know about your 2nd Pfizer or Moderna shot
- CA COVID-19 Vaccine Tracker: See your status here
- These CA counties are way ahead in vaccinations
- How to register for a COVID-19 vaccine in every Bay Area county
- Map shows everywhere you can get a COVID-19 test in the Bay Area
- Data tracker: Coronavirus cases, deaths, hospitalizations in every Bay Area county
- Get the latest updates on California EDD, stimulus checks, unemployment benefits
- Coronavirus origin: Where did COVID-19 come from?
- What is a COVID-19 genetic, antigen and antibody test?
- What does COVID-19 do to your body and why does it spread so easily?
- Coronavirus Timeline: Tracking major moments of COVID-19 pandemic in San Francisco Bay Area